Competition for patients with hepatitis C virus (HCV) genotype 1 infections, the most common in the U.S. is heating up. In addition to Harvoni (ledipasvir and sofosbuvir, Gilead Sciences Inc.) and Viekira Pak (ombitasvir, paritaprevir, ritonavir and dasabuvir, Abbvie Inc.), Merck & Co. Inc. gained FDA approval of its once-daily treatment, Zepatier (elbasvir and grazoprevir), earlier this year.